Primary Structure of Xenopus Cdc14α and Cdc14β phosphatases A. Schematic comparison of XCdc14α, XCdc14β and hCdc14A. The gray regions in hCdc14A correspond to the dual specificity phosphatase (DSP) domains identified in the crystal structure of hCdc14B. The nuclear export signal (NES), putative nuclear localization signal (NLS), and QGD repeats present in hCdc14A are conserved in XCdc14α and XCdc14β and are represented by shaded boxes. The asterisks represent the active site cysteines, and the circled "p" represents a canonical Cdk phosphorylation site (SPLK) located at residues 443–446 of XCdc14α. The solid lines at the bottom of the figure represent the regions of XCdc14α that were used for immunizations. Percentage identities between the subregions are indicated in grey. B. Alignment of the NLS, NES, and QGD sequences of hCdc14B, hCdc14A, XCdc14α and XCdc14β. Top left: hCdc14A, hCdc14B, XCdc14α, and XCdc14β contain putative bipartite NLS sequences that conform to the consensus motif (R/K)2X7–12(R/K)3,. The sequences are aligned with the bipartite NLS from nucleoplasmin. Top right: Alignment of the NES sequences that are present in all four Cdc14 homologs. The NES of hCdc14A was shown to be functional by mutational analysis . The "φ " in the consensus motif signifies hydrophobic amino acids. Bottom: Alignment of conserved C-terminal QGD motifs.